Systems and methods for heat recovery

ABSTRACT

A filter unit heat exchanger is provided that may include a housing substantially surrounding a heat exchange assembly. Provided through the housing are one or more tortuous fluid flow paths used to direct airflow therethrough around portions of the heat exchange assembly for efficient operation. The tortuous path(s) may be provided by one or more nozzle openings on an input side of the housing and one or more diffuser openings on an output side of the housing, where the nozzle openings and diffuser openings are offset to cause desired airflow deflection. The filter unit may include desired symmetries to improve manufacturability and/or installation.

The application is a continuation-in-part of U.S. patent applicationSer. No. 12/807,653, filed Sep. 10, 2010, the entirety of which isincorporated by reference herein.

This application is also related to U.S. Pat. No. 5,456,244, titled“Combination Cook Stove Fluid Heater and Grease Filter,” U.S. Pat. No.5,687,707, titled “Combination Cook Stove Heat Exchanger and Filter,”and U.S. Pat. No. 6,543,526, titled “Combination Cook Stove HeatExchanger, Filter, and Recirculation Assembly,” the entire disclosuresof which are incorporated by reference herein.

FIELD OF THE INVENTION

Embodiments of the present invention generally relate to air filtersand, more particularly, to an improved grease trap air filter that isalso used as a heat transfer device.

BACKGROUND OF THE INVENTION

Commercial or institutional kitchens generally include cook stoves, hotplates, deep fat fryers, and other cooking devices that produce heatenergy and particulates, i.e. grease. The extreme heat and particulatesmust be exhausted to atmosphere usually through flue chimneys or similarventing devices for the safety and comfort of the kitchen workers. Thisprocess replaces the hot kitchen air with cooler, clean outside air.Although this circulation process is necessary to provide a constantsource of clean air to the kitchen environment, it is inefficient anduneconomical, especially in colder climates where the cost to heatinternal air and water is significant.

Another problem encountered in commercial kitchens is that the generatedparticulates must be filtered. The particulates, that most commonlyincludes grease can eventually cause malfunction of air ventilationsystems, which may create fire hazards. Accordingly, air filters locatedin flume hoods positioned over cooking surfaces must be cleaned often,which is time-consuming and expensive.

Venting and filtering systems may employ heat exchangers to capturethermal energy from the hot gases. For example, some systems employ aheat exchanger positioned downstream of a grease filter. Thisconfiguration is unfavorable for many reasons. First, these designs maybe inefficient as the heat exchanger is usually located a significantdistance from the heat source, which means heat is lost before the hotair encounters the heat exchanger. That is, the thermal energy is lostthrough heat dissipation before the heat exchanger is reached. Second,the existing grease filters significantly impede air flow, especiallywhen congested with grease, which reduces the efficiency of the airventilation system as heat is absorbed by the filter before the hot airreaches the heat exchanger. Third, when the heat source is turned off,the grease quickly solidifies within existing filters, which usuallyinclude fins that capture and maintains the particulate matter.

Many existing kitchens fail to incorporate any kind of heat exchangerbecause of integration costs. Retrofitting existing kitchen equipmentwith heat exchanger systems may require an entirely new flue hoodassembly and substantial piping and accessories. Thus, conversion istime-consuming and expensive.

While some improvements have been made to combine a filter and heatexchanger, such as disclosed in U.S. Pat. No. 5,456,244, there remains aneed to provide a filter system of simplified construction and thatprovides more efficient heat transfer than existing devices. To addressthis long-felt need, one embodiment of the present invention is a systemfor filtering and heat capture that is efficient and that may beretrofitted into existing flue systems.

SUMMARY OF THE INVENTION

It is one aspect of some embodiments of the present invention to providea system that simultaneously filters grease and airborne particulatematter from hot gas flumes and transfers heat from the hot gas to acirculating fluid. The heated circulating fluid then transfers heat to aheat transfer medium, water, or air. The system of one embodiment can beretrofitted into existing flue hood ventilation systems of varyingdesigns and dimensions.

Embodiments of the present invention include systems and methods relatedto filter units having simplified construction, using less material andproviding more complete heat transfer than prior devices. Morespecifically, a filter unit according to one embodiment of the presentinvention comprises a housing generally comprised of a base and coverthat surrounds a heat exchanger. The housing includes at least oneentrance opening on an upstream side of the heat exchanger. The housingincludes at least one baffle on a downstream side of heat exchangeropposite the upstream side. At least one exit opening is also providedthrough the housing on the downstream side of the heat exchanger. The atleast one baffle may be aligned with the at least one entrance opening.In operation, hot gas is drawn through the at least one entrance openingand across the heat exchanger. The baffles will then redirect the gastowards the heat exchanger before the gas can leave the cavity throughthe at least one exit opening. In this way, hot air exposure to the heatexchanger is maximized.

It is another aspect of some embodiments of the present invention toprovide a heat exchanger that increases heat transfer efficiency. Morespecifically, the heat exchanger may employ a heat-conductive materialat least partially coated with a reduced friction material, such aspolytetrafluoroethylene. The reduced-friction material enhances fluidflow, thereby increasing the rate at which the hot gases encounter heattransfer elements of the heat exchanger. The reduced-friction materialalso allows any captured particulates to drip from the heat transferelements into a catch pan, instead of clinging to it.

Heat transfer is also increased by some embodiments of the presentinvention that employ an equal number of heat transfer fluid conduits,which may have equal surface area. Other embodiments of the presentinvention employ heat transfer fluid conduits that have heat exchangefins. The fins may surround one conduit or multiple conduits. The finnedconduits are positioned in the fluid flow cavity provided by thehousing, and increase thermal conductivity because the fins increasesurface area of the heat exchanger fluid conduits. Other embodiments thepresent invention employ heat exchanger fluid conduits having dimples,turbulators, or other surface irregularities that help dissipate heat.

These and other advantages will be apparent from the disclosure of theinvention(s) contained herein. The above-described embodiments,objectives, and configurations are neither complete nor exhaustive. Aswill be appreciated, other embodiments of the invention are possibleusing, alone or in combination, one or more of the features set forthabove or described below. Further, the Summary of the Invention isneither intended nor should it be construed as being representative ofthe full extent and scope of the present invention. Moreover, referencesmade herein to “the present invention” or aspects thereof should beunderstood to mean certain embodiments of the present invention andshould not necessarily be construed as limiting all embodiments to aparticular description. The present invention is set forth in variouslevels of detail in the Summary of the Invention as well as in theattached drawings and the Detailed Description of the invention and nolimitation as to the scope of the present invention is intended byeither the inclusion or non-inclusion of elements, components, etc. inthis Summary of the Invention. Additional aspects of the presentinvention will become more readily apparent from the Detail Description,particularly when taken together with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention andtogether with the general description of the invention given above andthe detailed description of the drawings given below, serve to explainthe principles of these inventions.

FIG. 1 is a perspective view of a filter unit according to oneembodiment of the present invention;

FIG. 2 is an exploded view of FIG. 1;

FIG. 3 is a cross-sectional view of FIG. 1;

FIG. 4 is a cross-sectional view of FIG. 2 showing a heat exchangeremployed by the embodiment of FIG. 1;

FIG. 5 is a perspective view of a base portion of a filter housingemployed by the embodiment of FIG. 1;

FIG. 6 is a perspective view of a cover portion of a filter housingemployed by the embodiment of FIG. 1;

FIG. 7 is a partial cutaway view of a venting and filtering system ofone embodiment of the present invention;

FIG. 8 is a schematic of another embodiment of a venting and filteringsystem;

FIG. 9 is a partial cutaway view of another embodiment of a closedventing and filtering system;

FIG. 10 is a front perspective view of a filter unit according toanother embodiment of the present invention;

FIG. 11 is a rear perspective view of FIG. 10;

FIG. 12 is a exploded view of FIG. 10; and

FIG. 13 is a cross-sectional view of FIG. 10.

To assist in the understanding of one embodiment of the presentinvention the following list of components and associated numberingfound in the drawings is provided herein:

# Component 100 Filter unit 110 Housing 112 Base 114 Cover 118 Base wall120 Lateral sidewall 122 Gap 123 Base cavity 124 Opening 124a Upstreamside 124b Downstream side 126 Fin 127 Fin plate 128 Retainer or tab 130Handle 132 Handle bracket 133 Drain hole 134 Plate 136 Lateral sidemember 138 Baffle 140 Opening 150 Airflow path 170 Heat exchanger 172Header pipe 174 Fluid flow conduit 176 Fluid flow chamber 178 Fluid port179 Threads 180 Vibration pad 200 Exhaust housing 202 Cooking surface203 Grease trap 204 Angle 205 Coupler 210 Supply tank 212 Conduit 214Storage tank 216 Water heating tank 218 Pump 220 Check valve 222Shut-off valve 310 Pump 312 Radiator 314 Heat exchanger 316 Roof 318Heat exchanger 320 Walkway 400 Filter unit 401 Fin 403 Fastener 404Flange 405 Hose 407 Pressure relief valve 408 Heat exchanger fin 412Base 414 Cover 418 Base wall 420 Lateral side member 423 Cavity 424Opening 424 Entrance opening 426 Fin 433 Drain hole 438 Baffle 440Opening 441 Fin 450 Fluid flow path 470 Heat exchanger 474 Fluid flowconduit

It should be understood that the drawings are not necessarily to scale.In certain instances, details that are not necessary for anunderstanding of the invention or that render other details difficult toperceive may have been omitted. It should be understood, of course, thatthe invention is not necessarily limited to the particular embodimentsillustrated herein.

DETAILED DESCRIPTION

FIGS. 1-3 and 5 depict a filter unit 100 according to one embodiment ofthe present invention that comprises a housing 110 and a heat exchanger170. The housing 110, which may be comprised of one or more components,generally surrounds the heat exchanger 170. For example, the housing 110may comprise a base 112 and a cover 114. The base 112 includes a basewall 118 and a plurality of lateral sidewalls 120. The base 112 may bestamped or otherwise formed of a planar sheet material, such as astainless steel sheet of a desired thickness. Once stamped, the lateralsidewalls 120 may be bent towards each other, thus forming a cavity 123.Alternatively, the sidewalls 120 may be coupled to the base wall 118,such as by welding. There may be a gap 122 (see FIG. 5) between adjacentsidewalls 120, or the gap 122 may be closed with a sealant or weld.Alternatively, the plurality of sidewalls 120 may be formed as a unitarymember, such as in a ring formation, and coupled to a base wall 118.Various shapes of the base, wall 118 are contemplated, although agenerally planar, rectilinear shape is shown, which will facilitatemanufacture and installation. In addition, such shape is easilyadaptable to be utilized with filter assembly units or exhaust hoodsthat are presently provided in commercial cooking settings. Furthermore,it is the shape of the filter unit 100 may be at least laterallysymmetrical, such that the unit may be inserted into a hood or exhaustassembly in a plurality of orientations, to provide ease ofconnectivity. Indeed, the filter unit may be rotationally symmetrical inat least one plane.

The base wall 118 is of one embodiment is perforate, including one ormore air portals 124 that allow air to pass into the base cavity 123.The openings 124 may be associated with fins 126 adapted to decrease theopening 124 size towards the cavity 113. A pair of fins 126 may beprovided for each opening 124, wherein each fin 126 extends into thecavity 123. This configuration acts as a nozzle, wherein each opening iswider at its upstream side 124 a and narrower at its downstream side 124b. The fins 126 may be formed from the same material as the base wall118, and may be stamped and formed from the same piece of material asthe base wall 118, and then bent into the cavity 123. Alternatively, thefins 126 may be provided as separate components that are stationarilycoupled with respect to the base wall 118. If provided as separatecomponents, two fins 126 may be provided as coupled together, perhaps asa unitary member including a fin plate 127 disposed between the two fins126. The fin plate 127 may include a substantially planar surfaceextending along a length, proximate end portions of which are secured tothe base wall 118. The nozzling function provided by the arranged fins126 focuses the airflow towards a baffle 138 included on the cover 114or disposed on the opposite side of the heat exchanger 170 from the fins126. This configuration therefore assists in the collection of greaseparticles. In addition, the airflow path creates turbulence thatincreases exposure time of the air with the heat exchanger 170.Accordingly, one embodiment of the present invention allows no directairflow path through the filter assembly 110, or a majority of theairflow therethrough is not direct. Indeed, as shown in FIG. 3, the finsand baffles reverse airflow to a path oriented about 45-180° from thedirection of flow at the upstream side of the filter unit. One or moretortuous airflow paths 150 are created, thereby creating turbulent flowthat exposes the heat exchanger 170 to heated air for a sufficientamount of time to allow for adequate heat exchange to a fluid flowingthrough the heat exchanger 170.

One or more retainer tabs 128 are formed on at least one of the lateralside members 120 of the base 112. The retainer tabs 128 may be on twoopposing lateral side members 120. A retainer tab 128 is extruded fromthe lateral side number 120 so as to provide a resiliently deflectableretaining member. Also provided on the base 112 is at least one handle130, which may be formed in a variety of ways. The handles 130 areprovided in opposing positions on the filter unit 100 to allow forbalanced insertion and removal of the filter unit 100 from an exhaustsystem. The handles 130 are full or partially wire loop handles that aresuspended from handle brackets 132 that may be formed integrally with orcoupled to the base wall 118.

The filter unit 100 according to some embodiments of the presentinvention serves as an air filter that assists in the collection ofgrease particles, which is especially advantageous to be used overcommercial cooking surfaces. To aid in the drainage of collective greaseparticles, the base 112 may be provided with one or more drain holes133. A plurality of drain holes 133 may be employed which may be formedalong the juncture of one or more lateral side members 120 and the basewall 118.

Referring now to FIGS. 2, 3, and 6, the cover 114 comprises a plate 134,and may further include one or more lateral side members 136 extendingfrom the plate 134. The side members 136 are inserted between headerpipes 172 of the heat exchanger 170. Furthermore, the side members 136may be formed with one or more heat exchanger interfaces which maycontact and/or surround a portion of the heat exchanger 170 to maintainposition during and after installation. The cover 114 may be formed as asymmetrical shape that may be inserted into the base 112 in a pluralityof orientations.

One or more baffles 138 are formed integrally with or coupled to theplate 134. The baffles 138 are disposed opposite the entrance openings126 formed in the base 112. The cover 114 also includes at least oneopening 140 similar to that provided by the base. The baffles 138 act asa one or more diffusers, such that upstream side 140 a of the openings140 disposed between the baffles 138 is smaller than the downstream side140 b. The baffles 138 may be formed similar or identical to the unitaryfin members, discussed above. A flow construction created by the baffles138 restrict and redirect flow laterally to create the tortuous airflowpath 150 that aids in the collection of grease and maximizes heattransfer to the heat exchanger 170.

The filter base 112 and cover 114 are formed of stainless steel, thoughother materials are contemplated, such as aluminum, copper, steel, andother materials adapted to transfer heat. A plastic housing could alsobe used. However, plastic has demonstrated affections for grease, whichmay be caused by its insulative properties, and therefore it may requiremore frequent cleaning.

The heat exchanger 170 is formed from two header pipes 172, which may beprovided in a parallel arrangement, and a plurality of fluid flowconduits 174, which also may be provided in a parallel arrangement,extending between the two header pipes 172. The heat exchanger 170 issized to be positioned substantially within the cavity 123. A fluid flowchamber 176 is provided within the header pipes 172 and conduits 174. Afluid may be a potable fluid, such as water, or propylene glycol. Whilethe heat exchanger 170 could be formed asymmetrically, it is at leastrotationally symmetrical in at least one plane, such that it may beinserted into the cavity 123 in a plurality of orientations. In oneembodiment, each header 172 is provided with a fluid port 178 in fluidcommunication with the fluid flow chamber 176. The ports 178 may beprovided with threads 179 or other coupling mechanisms, such as a fluidquick connect coupling that interfaces to a fluid supply or drain. Inone embodiment of the present invention, the ports 178 are provided onopposite ends of their respective header 172. Vibration pads 180 may beprovided on one or more components of the filter unit 100. A pluralityof pads 180 may be adhered to each header pipe 172 in the heat exchanger170. The vibration pads 180 cooperate with the base wall 118 to preventa rattling of two or more components.

A material for one or more components of the heat exchanger is copper,which may be coated with a non-stick material, such as a paint includingpolytetrafluoroethylene, available as a Teflon® material, available fromE.I. du Pont de Nemours and Company of Wilmington, Del. The non-stickmaterial may be painted onto the desired heat exchanger components.Another acceptable material for the heat exchanger headers 172 andconduits 174 is steel tube, which may also be painted with a non-stickmaterial.

Generally, systems and methods according to some embodiments of thepresent invention collects heat generated by a cooking surface, whichwould otherwise be wasted as exhaust, and transfer such heat to otherlocations for use in an open or closed circulation system. As shown inFIG. 7, one or more filter units 100 may be installed in an exhausthousing 200 above a cooking surface 202. While the filter 100 could beinstalled at any desirable angle, such as horizontal, some embodimentsinclude a filter 100 installed at an angle 204 relative to horizontallevel. The angle 204 may be between about 12 degrees to about 45 degreesto allow collected particles to drain. In this configuration, thelongitudinal dimension of the fins and baffles are disposed atapproximately the same angle. Thus, collected particles will drain fromthe drain holes and into one or more grease traps 203. As further shownin FIG. 7, a plurality of filter units 100 may be coupled together toform an expanded filter unit. The units 100 may be coupled in series, asshown, or in parallel. If coupled in series, a coupler 205 may beconnected at one end to a port 178 of one filter unit 100A and at theother end to a supply port 178 of a subsequent filter unit 100B.

FIG. 7 depicts an open system. Here, the heated fluid flowing throughthe heat exchangers is removed and put to some other use, such asdishwashing, or it is stored for future use. Water or other desirablefluid may be provided by gravity feed, such as from an elevated supplytank 210 or municipal water supply, or it may be pumped to the system.Conduit 212 and standard connections may couple the water supply to afirst filter unit 100A. The fluid flows through one or more filter units100, and then drain into a storage tank 214 for future use, such as by adishwasher, hot water supply in a restroom, or for other purposes.

Another example of an open system is shown in FIG. 8. Here, in additionto the storage tank 214, this system includes a water heating tank 216and a recirculating pump 218. The associated plumbing includes variouscheck valves 220 and shut-off valves 222. One advantage to this enhancedsystem is that if fluid usage exceeds the supply of heated fluid, fluidstored in the storage tank 214 may be recirculated to keep the water inthe plumbing system warm. The recirculating pump 218 may be selectivelyactivated and deactivated with a timer or as a function of a measuredtemperature of the fluid in the storage tank 214.

FIG. 9 shows a closed system, that uses heat from the exhaust gaseselsewhere. In this system, water or other fluid is introduced andsubstantially all of any residual air is purged. The fluid may be pumpedthrough the system by an inline pump 310, through conduit 212 andthrough one or more filter units 100. After traveling through the one ormore filter units 100, in which the fluid is heated by exhaust from thecooking surface 202, the fluid travels through one or more additionalheat exchangers. For instance, the fluid may be pumped to a radiator 312to heat a room. Additionally or alternatively, the fluid may be pumpedthrough a roof heat exchanger 314 disposed along the edge of the roof316 of the building to prevent ice damming. The fluid may be pumpedthrough a sidewalk heat exchanger 318 disposed beneath or embedded in aconcrete or other external walkway 320 to reduce the buildup of icethereon. It is to be appreciated that the function of a system accordingto some embodiments of the present invention may be changed dependingupon the time of year. For instance, in summer months, it may not bedesirable to use a closed system for heating as described above. In suchsituations, the fluid may remain static and the filter units 100 may beused to collect particulates from the exhaust air. Alternatively, theclosed system could be changed to an open system in the summer months,thereby providing hot water for use. Those of skill in the art willappreciate that the heat energy can be converted to electrical ormechanical energy using common methods.

FIGS. 10-13 show a filter unit 400 of another embodiment of the presentinvention. Similar to the embodiments described above, filter unit 400includes a base 412 interconnected to a cover 414. The cover 414 and abase wall 418 of the base 412 define a cavity 423 that surrounds theheat exchanger 470 that receives the airflow 450. As in the embodimentsdescribed above, the base 412 includes a plurality of fins 426 thatdirect airflow into the cavity 423. Here, however, the openings 424 arebounded by the fins 426 and a fin 401 that is generally parallel to thebase wall 418. The fin 401 directs gas towards the angled fins 426 anddefine a circuitous flow path 450, which is described in further detailbelow.

Similarly, the cover 414 includes a plurality of baffles 438 that areangled into the cavity 423. Again, the baffles 438 define an exitopening 440. A fin 441 is positioned between adjacent baffles 438 andhelps shield the fluid conduits 474 of the heat exchangers 470.Accordingly, a fluid flow path 450 is provided that redirects or atleast partially reverses fluid flow. As gas enters the entrance opening424, it is directed by the fin 401 and the fins 426 into contact with abaffle 438. These features redirect fluid flow between about 45-180°from its original path, which increases contact with fluid conduits 474.The base wall 418 and fin 426 of an adjacent entrance opening 424 willthen direct the redirected airflow so it will exit the space between thebaffle 438 and the fin 441. In this fashion, the hot air exposure to thefluid conduits 474 is dramatically increased without unduly slowingfluid flow.

As shown in FIG. 12, the fluid flow conduits 474 may include a pluralityof heat exchanger fins 408. The fins 408 may extend the entire length ofthe fluid flow conduits 474 or portion thereof. Further, the fins mayencapsulate one or more fluid flow conduits 474. Some of the fluid flowconduits 474 do not include exchanger fins 408. The exchanger fins 408increase the amount of surface area that contact the hot gas.

FIG. 12 also shows that the cover for 12 may be interconnected to thebase for 12 by way of a plurality of fasteners 403 in incorporated ontoa flange 404.

FIG. 11 also shows a pressure relief valve that opens when high-pressureis encountered within the system which is a safety feature.

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways. Also, it is to be understood thatthe phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items.

What is claimed is:
 1. A filter unit comprising: a housing including acavity; a heat exchanger disposed substantially within said cavity; anentrance opening provided through said housing on an upstream side ofsaid heat exchanger; a first angled fin associated with a first lateraledge of said entrance opening; a second angled fin spaced from saidfirst angled fin, said second angled fin associated with a secondlateral edge of said entrance opening; a third fin positioned betweensaid first angled fin and said second angled fin; an exit openingprovided through said housing on a downstream side of said heatexchanger, said downstream side being oppositely disposed of saidupstream side; a first angled baffle associated with a first lateraledge of said exit opening; and a second angled baffle spaced from saidfirst angled baffle, said second angled baffle associated with a secondlateral edge of said exit opening.
 2. The filter unit of claim 1,further comprising a third baffle positioned between said first angledbaffle and said second angled baffle.
 3. The filter unit of claim 1,wherein said heat exchanger is comprised of a plurality of fluidconduits, wherein at least one of said plurality of fluid flow conduitsinclude at least one fin.
 4. The filter unit of claim 1, wherein saidhousing comprises a base and a cover.
 5. The filter unit of claim 4,wherein said base comprises a substantially planar base wall having abase wall perimeter; and a plurality of lateral sidewalls coupled tosaid base wall perimeter substantially encircling said base cavity,wherein said entrance opening is formed through said base wall.
 6. Thefilter unit of claim 5, wherein said first fin and said second finextend at least partially across said entrance opening and into saidcavity at an oblique angle relative to said base wall, and said thirdfin is parallel to said base wall.
 7. The filter unit of claim 5,wherein said exit opening is provided in a wall of said cover that isgenerally parallel to said base wall, and wherein said first baffle andsaid second baffle extend at least partially across said exit openingand into said cavity at an oblique angle relative to said wall, and saidthird baffle is parallel to said wall.
 8. The filter unit of claim 1,wherein said heat exchanger comprises: a first header; a second headerpipe spaced from said first header pipe; at least one fluid flow conduitdisposed between and in fluid communication with said first header pipeand said second header pipe; a first fluid port provided on said firstheader pipe; and a second fluid port provided on said second headerpipe.
 9. The filter unit of claim 8, wherein said at least one fluidflow conduit comprises spaced fluid flow conduits that are disposedsubstantially perpendicular to said first header pipe and said secondheader pipe.
 10. The filter unit of claim 9, wherein at least one pairof adjacent fluid flow conduits are interconnected with a plurality ofheat exchange fins.
 11. The filter unit of claim 9, wherein a third anda fourth fluid flow conduits, a sixth and a seventh fluid flow conduits,and a ninth and tenth fluid flow conduits comprise conduit pairs thatare interconnected with a plurality of heat exchange fins.
 12. Thefilter unit of claim 8, further comprising a pressure relief valveinterconnected to said second header pipe.
 13. A system comprising: acooking surface including a heat source; an exhaust system adapted todraw in gasses that are disposed above said cooking surface, saidexhaust system providing a gas flow path for the gasses; a filter unitdisposed in said gas flow path, said filter unit comprising: a housingincluding a cavity; a first heat exchanger disposed substantially withinsaid cavity, said first heat exchanger including a fluid input port anda fluid output port; at least one entrance opening provided through saidhousing on an upstream side of said first heat exchanger; a first angledfin associated with a first lateral edge of said at least one entranceopening; a second angled fin spaced from said first angled fin, saidsecond angled fin associated with a second lateral edge of said at leastone entrance opening; at least one exit opening provided through saidhousing on a downstream side of said first heat exchanger, saiddownstream side being oppositely disposed of said upstream side; a firstangled baffle associated with a first lateral edge of said at least oneexit opening; a second angled baffle spaced from said first angledbaffle, said second angled baffle associated with a second lateral edgeof said at least one exit opening; wherein said first and second angledbaffles are aligned with said at least one entrance opening, such thatwhen the gasses are drawn through said at least one entrance opening andacross said first heat exchanger, said first and second baffles redirectthe gasses towards the first heat exchanger before the gasses can exitsaid housing through the at least one exit opening; a fluid supplycoupled to said input port; a drain line coupled to said output port andto at least one of a storage tank and a second heat exchanger.
 14. Thesystem of claim 13, further comprising a third fin positioned betweensaid first angled fin and said second angled fin.
 15. The system ofclaim 13, further comprising a third baffle positioned between saidfirst angled baffle and said second angled baffle.
 16. The filter unitof claim 13, wherein said first heat exchanger is comprised of aplurality of fluid conduits, wherein at least one of said plurality offluid flow conduits include at least one fin.
 17. The system of claim13, wherein said second heat exchanger is at least one of a radiatoradapted to heat an indoor space, a length of heat-conductive tubingdisposed in or below a walking surface, and a length of heat-conductivetubing disposed on a roof of a building.
 18. The system of claim 13,wherein said first heat exchanger is angled relative to said cookingsurface.
 19. The system of claim 18, wherein the angle between saidcooking surface and said first heat exchanger is from about 10 degreesto about 60 degrees.